Diagnosing The Risks

In the three weeks since the Sept. 11 attacks, Americans have become increasingly concerned that the next one might be even worse. In the TIME/CNN poll taken last week, 53% of those surveyed feared a chemical or biological attack; 23% a nuclear strike. Among terrorism experts, however, the focus has shifted from a single large-scale assault--which would be difficult to pull off--to a series of smaller attacks that could be just as damaging to the U.S. economy and public morale. How serious are these threats? What form might they take? The best guesses of the experts consulted by TIME offer both...